1. Field of the Invention
The present invention is generally directed to new methods and machines for cutting metals, such as steel. More specifically, the present invention is directed to a process and apparatus by which steel is quickly cut so as to increase production capacity for steel fabrication, ship building, ship repair and heavy equipment production.
2. Background of the Invention
The traditional method of metal cutting involves the use of cutting torches that use oxygen and acetylene gases. The cutting torch operator sets the oxygen gas pressure level to about 40 to 60 pounds per square inch and sets the acetylene gas pressure level to about 8 to 12 pounds per square inch. With the cutting torch tip generally perpendicular to the surface it is cutting, the operator uses the cutting torch to heat the metal in a local area until it becomes about molten, and then applies additional oxygen to heat up the metal even more, thereby reducing the viscosity of the molten metal. With the same oxygen blast, the molten metal is blown out the other side of the metal plate. With the torch in a generally perpendicular position, the operator slowly moves the cutting tip manually along the proposed cutting line. The process of cutting steel is therefore a very slow and tedious process. Metal workers in shipyards, factories, and assembly shops across the country spend countless hours cutting steel from steel plate in desired shapes and sizes.
Conventional flame cutting machines cut with low pressures at relatively slow speeds. A current “high speed” track torch will cut through one-quarter inch steel plate no faster than about 24 inches per minute. Usually, the track torch will only be utilized at speeds of no faster than 16 inches per minute. Typically, a cutting torch uses oxygen and acetylene at 40 to 60 pounds per square inch and 8 to 12 pounds per square inch pressure levels, respectively.
In more advanced cutting machines that employ plasma arc cutting techniques, the machines are capable of moving up to 70 inches per minute. Although these machines are much quicker than conventional cutting torch machines, they are complex and very expensive to own and operate.
Another disadvantage of the current cutting machines and methods is that the due to the generally perpendicular positioning of the cutting torch tip or plasma arc tip with respect to the cutting surface, the cutting torch tends to cut not only the work piece but also the member that holds the work piece in place. For example, a steel plate is typically positioned on and supported by a cutting table. When the steel plate is cut, the supporting cutting table is also cut because the cutting flame from the cutting torch extends through the work piece and into the cutting table. Similarly, when a steel plate is on the side of a ship or attached or welded to a frame or other steel members, the frame or other steel members are damaged by the cutting torches when cutting the steel plate.
Still another disadvantage of conventional cutting machines and methods is that portions of the work piece becomes insulated from the heat of the flame and flowing oxygen which causes the prior art cutting machines to lose the cut, slow down, or have imperfect cuts that have to be re-cut. The work piece becomes insulated from the heat due to certain conditions of the metal, i.e., the work piece may be covered or partly covered with paint, rust or mill scale. Another reason is the occasionally improper setting of the torch height or heat output, either by the operator or by the computer numerical control (CNC).
Throughout the United States and the world, heavy industry has a dire need for faster, cheaper methods and machines for cutting metals in shipyards, factories and steel fabrication lots. As such, a need currently exists for an improved method and machine for cutting metal.
In view of the foregoing problems with the conventional art, a need exists for an improved method and machine for cutting metal that is faster, less expensive, produces a smoother cut, eliminates the problems of rust, mill scale and paint, and is capable of generally preserving the structure which supports the work piece.